This invention relates to the decontamination of toxic chemical agents in which a decontaminating agent is entrapped within a macroporous cross-linked copolymer. The copolymer is a powder which is a complex structure consisting of unit particles, agglomerates, and aggregates.
The concept of producing spheres or beads by means of suspension polymerization techniques is well known in the prior art. An exemplary one of such processes is disclosed in U.S. Pat. No. 2,809,943, issued Oct. 15, 1957. However, it was found that when a material was added which is a solvent for the monomers, but acts as a precipitant for the resulting polymer, a novel form of bead was provided containing a network of microscopic channels. This discovery is set forth in U.S. Pat. No. 4,224,415, filed Jul. 18, 1958, issuing some twenty-two years later on Sep. 23, 1980. In this patent, beads are produced ranging in size from about 350 to about 1200 microns. Typical monomers include divinyl toluene, diallyl maleate, and triallyl phosphate. The precipitant employed is an alkane, acid ester, or alcohol.
This technology was expanded and the precipitant was variously described in the patent literature as a diluent, porogen, active ingredient, solvent, functional material, and volatile agent. For example, in U.S. Re. Pat. No. 27,026, issued Jan. 12, 1971, porous beads of a diameter less than ten microns are disclosed. Among the monomers used to produce the beads are ethyl methacrylate, divinyl benzene, and ethylene glycol dimethacrylate. In U.S. Pat. No. 3,418,262, issued Dec. 24, 1968, there is described a bead characterized as having a rigid sponge structure, and wherein the porogenic agent employed is an acid such as stearic acid. Intermediates in bead form were produced in U.S. Pat. No. 3,509,078, issued Apr. 28, 1970, using polymeric materials such as polyethylene glycols as the precipitant material during the in situ suspension polymerization process. The macroporous character of such bead construction is graphically portrayed and illustrated in FIG. 1 of U.S. Pat. No. 3,627,708, issued Dec. 14, 1971. Beads termed "pearls" are produced, and containing active ingredients therein such as water or various alcohol ethers. The pearls are crosslinked to the extent of about twenty percent. In U.S. Pat. No. 3,637,535, issued Jan. 25, 1972, beads with a sponge structure are said to be capable of being compressed to an imperceptible powder. These beads are capable of being loaded with as much as 200-300% of active ingredients such as white spirit, and benzin. A rigid porous bead of a trifunctional methacrylate is taught in U.S. Pat. No. 3,767,600, issued Oct. 23, 1973. Such beads have a size of 10-900 microns, and various other monomers which can be employed include diacetone acrylamide, and ethylhexyl, hydroxyethyl, and hydroxypropyl methacrylates. Paraffin wax in an amount of 5-100% is used to form the microscopic network of channels in U.S. Pat. No. 3,989,649, issued Nov. 2, 1976. The wax may be removed from the bead structure by solvent extraction.
While many of the foregoing U.S. patents relate to ion exchange technology, a bead similar to those previously described is employed as a carrier for enzymes in U.S. Pat. No. 4,208,309, issued Jun. 17, 1980. Such beads are of the size of about 0.1 mm. U.S. Pat. No. 4,661,327, issued Apr. 28, 1987, describes a macroreticular bead containing a magnetic core. The use of hard crosslinked porous polymeric beads in cosmetics as carriers is taught in U.S. Pat. No. 4,724,240, issued Feb. 9, 1988, wherein various emollients and moisturizers are entrapped therein. These beads are said to be capable of entrapping materials such as 2-ethylhexyl oxystearate, arachidyl propionate, petroleum jelly, mineral oil, lanolin, and various siloxanes. The size of the beads ranges from 1-3,000 microns. Typical monomers include ethylene glycol dimethacrylate, lauryl methacrylate, trimethylol propane trimethacrylate, and dipentaerythritol dimethacrylate. "In situ" hydrophobic powders and "in situ" beads may be produced in accordance with the teaching of this patent. Beads having a rigid sponge structure are also described in U.S. Pat. No. 4,690,825, issued Sep. 1, 1987, and wherein the beads function as a delivery vehicle for a host of materials including pigments, vitamins, fragrances, drugs, repellants, detergents, and sunscreens. The beads have a size of 10-100 microns and are preferably of a monomer system of styrene-divinyl benzene. Crosslinking is said to range from 10-40 percent. U.S. Pat. No. 4,806,360, issued Feb. 21, 1989, describes a post adsorbent bead which contains a melanin pigment for use as a sunscreen.
The foreign patent literature includes West German Offenlegungsschrift No. P-2608533.6, published Sep. 30, 1976, and wherein porous polymeric beads produced by "in situ" suspension polymerization are provided, and which are adapted to release perfumes. A controlled release of the fragrance is disclosed, providing utility for such beads in the home, automobiles, airplanes, railway cars, hospitals, classrooms, conference centers, and gymnasiums. Canadian Patent No. 1,168,157, issued May 29, 1984, describes hard, discrete, free flowing, bead constructions in which the beads entrap a series of functional materials which can be incorporated into toilet soap, body powder, and antiperspirant sticks. The Canadian Patent, it is noted, is the equivalent of European Patent No. 61,701, issued on Jul. 16, 1986, both of which are foreign equivalents of the parent case of the '240 patent. In European International Publication No. 0252463A2, published Jan. 13, 1988, there is disclosed a bead having a hydrophobic polymer lattice, and which entraps numerous non-cosmetic materials such as pesticides, pharmaceuticals, pheromones, and various categories of chemicals. Steroids are entrapped, for example, in the porous beads of PCT International Publication No. WO-88/01164, published on Feb. 25, 1988. The steroids are adrenocortical steroids or various anti-inflammatory type steroids. It should therefore be apparent that what began as a simple ion exchange bead concept has rapidly grown into a technology of widely varied application.
In accordance with the present invention, copolymer powders are produced by novel processes not believed to be taught in the prior art, as exemplified by the foregoing patents. Those patents, in general, relate to suspension polymerization processes for the production of porous polymeric and copolymeric spheres and beads in which the precipitant is present during polymerization. These are defined as an "in situ" process. For example, U.S. Pat. No. 4,724,240, discloses beads and spheres produced by "in situ" suspension polymerization techniques. The PCT International Publication, while a suspension polymerization system, can also be defined as a "post adsorption" process in its use. In this variance, a volatile porogen is included which may be removed by extraction and evaporation, resulting in empty beads. The beads can be loaded with diverse active ingredients, as desired, at subsequent times. A similar process is disclosed in U.S. Pat. No. 4,806,360. "Post adsorption" techniques are more attractive because of the flexibility in the selection of active ingredients that can be subsequently entrapped, whereas in the conventional "in situ" systems, the porogen polymerized "in situ" remains in the final product.
Thus, according to the prior art, hydrophobic crosslinked porous copolymers in particle form can be produced by at least three distinct processes. One process produces beads by "in situ" suspension polymerization, and this process is shown in Example 4 of the '240 patent, and in U.S. Pat. No. 4,690,825. Another process produces beads by suspension polymerization but the beads are "post adsorbed" with an active ingredient after the volatile porogen is removed. This process is shown in U.S. Pat. No. 4,806,360, and in the PCT International Publication. In a third process, powders are produced by "in situ" precipitation polymerization, and this process is shown in Examples 1-3 of the '240 patent.
What has been accomplished in accordance with the present invention, however, is a unique concept differing from all of the foregoing methods, and wherein post adsorbent powders are produced and employed in a novel fashion in decontaminating surfaces contaminated with toxic chemical agents. Toxic chemical agents are chemical substances in gaseous, liquid, or solid form, intended to produce casualty effects ranging from harassment to incapacitation to death. Some particular effects produced by such toxic chemical agents can be choking, blood poisoning, lacrimation, nerve poisoning, laxation, and various forms of mental and physical disorganization and disorientation. In the event that decontamination cannot be properly handled by natural processes such as wind, rain, dew, sunlight, heat and actinic rays from the sun, some form of chemical decontamination must be employed.
Typical of the prior art systems for decontamination are the use of powders such as carbon, fuller's earth, bentonite, and other polymer systems; and solutions of bleach, various solvents, and various emulsions, which are sprayed or wiped over the contaminated surfaces with an applicator. Such methods suffer from the disadvantage that the solutions are corrosive and in many cases toxic. Further, there is a need for water which is not always convenient. These prior art techniques are generally not suited for indoor use on interiors, and are difficult to employ in low temperature regions of the country. The powders are also ineffective against toxic chemical agents when the agents are in their thickened form.
Thus, it should be apparent that there exists a need for a radically different and effective decontaminating agent for decontaminating various surfaces subject to toxic chemical agent contamination. The present invention fulfils such a need and provides a new decontaminating system which has a reduced toxic effect, does not depend on the use of water in order to function, and is capable of use at low temperatures. While cellular polymeric materials are not new to chemical warfare as indicated in U.S. Pat. No. 4,708,869, issued Nov. 24, 1987, the porous copolymeric powders of the present invention are employed to function as a vehicle for the decontaminating agent rather than for the toxic chemical agent as in the '869 patent.